Note: Descriptions are shown in the official language in which they were submitted.
CA 02471714 2004-06-23
Description
INORGAN2C POROUS FINE PART2CLES
Technical Field
The pz:esent invention re7.ates to a sol of a fine
particulate inorganic porous substance, a synthetic
method and uses thereof, and an ink--jet recording medium
such as a paper, a sheet, a film or a cloth for ink-jet
recording to be used in ink-jet px-inting and z"ecording
using the same, and a coating liquid for an ink-jet
recording medium to be used in the production thereof.
Background Art
Tecb.~zologies to which inorganic fine particles
are applied are attracting attention froze the viewpoints
of not only functional improvement of electronic
materials but aJ.so energy sa~ring, environmental
protection, and the like.
Inorganic fine particles are prepared mainly by a
vapor-phase process or a liquid-phase process, and oxides
such as Aerosil and colloidal silica and metal fine
particles such as gold colloid are known. Most of them
are solid particles having no Fore inside the partzcles_
On the other hand, as inorgazz:~c amorphous porous
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substances, there are known gel substances such as silica
gel and alumina gel having pores between particles,
amorphous active carbon and the like, but they generally
have a large particle diameter.
JP 9-0702SS B and the like disclose porous
spherical silica fine particles but they have a small
pore diameter and an irregular pore shape. Inorganic
porous fine particles synthesized using a template are
shown in Chem_ Lett_, (2000) 1044, Stu. Sur. Sci. Catal_,
129 (2000) 37, and JP 2000-109312 ~, but precipitates are
given in each case and a sol in which fine particles are
dispersed is not obtained_ JP 11-100208 A discloses a
rod-like meso-porous powder having a large aspect ratio,
but a precipitate occurs since a cationic surfactant, a
metal silicate and an acid are used, and a sol in which
fine particles are dispersed is not obtained. USP
6096469 discloses a porous sol synthesized using a
template but the template is not removed in examples and
a porous sol is not realized. W002/00550 discloses a
porous sol of fine particles hut their aspect ratio and
the degree of aggregation are riot described therein.
ink-jet recording has been now utilized in wide
fields because it causes less noise upon recording,
facilitates colorization and enables high~speed recording.
Bowever, quality paper for use in general printing is
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inferior in ink absorbing property and drying property
and also inferior in image quality such as resolution.
Therefore, special papers improving the properties have
been proposed, so that recording papers on which various
inorganic pigments including amorphous silica are applied
for improving the color-developing property of ink and
the reproducibility are disclosed (~P 55-051583 A, JP 56~
148585 A, and the like). With recent progress of
performance of ink-jet painters, further improvement of
performance is required on a recording medium and a
satisfactory performance cannot necessarily be obtained
by the above technology alone. In particular, there can
be cited insufficient ink absorbing property and
occurrence of blurs, owing to ~.ncreased discharging
amount of ink per unit area of a recording medium for the
purpose of obtaining a high image quality equivalent to
silver halide photograph. Furthermore, in order to
realize a high image quality and color density comparable
to silver halide photograph, transparency of an ink-
absorbing layer is also required.
JP 10-016379 A discloses an ink-jet paper using
inorganic fine particles having a high aspect ratio, but
the paper uses nonTporous plate-like fine particles and
tends to be inferior in ink absorbing property as
compared with a porous one. ~1P 10329406 A and JP 10-
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166715 A disclose recording sheets using silica particles
connected in a beads foam, but since the silica particles
used therein are non-porous, ink absorbing property tends
to be inferior as compared with the case of porous
particles.
The invention pro~crides a sol of an inorganic
porous substance having a small particle diameter and a
uniform pore diameter and a synthetic method thereof.
The invention also provides uses of the same, in
particular, an inl~-jet recording medium excellent in ink
absorbing property, transparency, water resistance and
light resistance, and a coating liquid for an ink-jet
recording medium.
Disclosure of the Invention
Namely, the present invention relates to the
following_
(1) R, sol containing an inorganic porous
substance, the inorganic porous substance having an
average particle diameter of ~.0 nm to 400 nm, as measured
by the dynamic light scattering method, an average aspect
ratio of its primary particles of 2 or more and meso-
poxes having a uniform diameter, and suffering from
substantially no secondary aggregation.
(2) The sol according to {1), wk~erein the meso-
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pores extend in the longitudinal direction_
( 3 ) The sol according to ( 1 ) or (2 ) , wherein the
inorganic porous substance has a difference between a
converted specific surface area SL determined from an
average paxticle diameter Z7L of particles measured by
dynamic light scattering method and a nitrogen-absorption
specific surface area S8 of particles by the SET method,
SB - SL, is 250 m2/g ox more _
(4) The sol according to any one of (2) to (3),
wherein the average aspect z~atio is 5 ox more.
(5) The sol according to any one oP (1) to (4),
wherein the inorganic porous substance comprises silicon
oxide.
(6) The sol according to (S), wherein the
inorganic porous substance contains aJ.uminurn_
(7) The sdl according to any one of (1) to (6),
wherein the meso-pores have an average diameter of 6 nm
to 18 run.
(S) The sol according to any one of (1) to t7),
wherein the inorganic porous substance has, bonded
thexeto, a compound containing an organ~.c chain.
(9) The sol according to (8), wherein the
compound containing an organic chain is a silane coupling
agent.
(7.0) The sol according to (9), wherein the silane
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coupling agent contains a quaternary ammonium group
and/or an amino group_
(1~) The sol according to any one of (1) to (10),
wherein the inorganic porous substance contains one
connected in a beads form and/or branched one.
(12) A porous substance obtained by removing a
solvent from the sol according to any one of (1) to (11).
(13) A process for producing a sol containing an
inorganic porous substance, comprising a step of mixing a
metal source comprising a metal oxide and/or its
precursor, with a template and a solvent to produce a
metal oxide/template complex, and a step of removing the
template from the complex, wherein in the mixing step
addition of the metal source to a template solution or
addition of a template solution to the metal source is
conducted and the addition period thereof is 3 minutes or
longer.
(14) The process according to (13), wherezn the
addition period is 5 minutes ar longer.
(15) The process according to (13) or (14),
wherein the metal source zs active silica.
(16) The process according to any one of (13) to
(15), wherein the template is a nonionic surfactant.
(17) The process according to (z6), wherein the
template is a nonionic surfactant represented by the
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following structural formula (1):
RO(CzHaO)a-(C3H6~)bW ~2H40)~R (1)
wherein a and c each represent from 10 to 110, b
represents from 30 to 70, and R represents a hydrogen
atom or an alkyl. group having 1 to 12 carbon atoms,
and wherein the metal source, the template and the
solvent are anixed at a weight ratio (solvent/template) of
the solvent to the template in the range of 10 to 1000.
(18) The process according to any one of (13) to
(17?. wherein a iaeight ratio (template/Si02) of the
template to an Si02-converted weight of active silica as
the metal source is in the rar~ge of 0.01 to 30_
(19) The process according to any dne of (13) to
(18), which further comprises a step of adding an alkali
aluminate.
(20) The procESS according to any one of (13) to
(19), wh~.ch comprises a step of regulating pH to 7 to 10
by adding an alka.~i, after mixing the metal source
comprising the metal oxide and/or its precursor, with the
template and the solvent.
(21) The process according to any one of (13) to
(20), wherein the removing step is conducted by
ultra~iltration_
(22) The process according to (21), wherein a
hydrophilic membrane is used as a f~.ltrating membrane for
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the ultrafiltration.
(23) The process according to any one of (13) to
(20), wherein the removing step is conducted by adding a
silane coupling agent and them, regulating pH to the
vicinity of an zsoelectric point to cause gelation and,
after the removing step, pH is regulated so as to be
apart from the isoelectric point to effect dispersion.
(24) The process according to any one of (13) to
(23), wherein the sol is cooled, in the removing step, to
a micelle-forming temperature of the template or lower.
(25) The process accoxding to any one of (13) to.
(24), which comprises a step of concentration by
distillation after the removing step_
(26) The process according to any one of (13) to
(25), whexein the template removed from the metal
oxlde/template complex is re-used.
(27) The process according to (26), which
comprises a step of heating a solution containing the
template removed fxom the metal. oxide/template complex to
a micelle~forming temperature or higher and concentrating
the template by ultrafiltration, for the re-use of the
template.
(28) The process according to (27), wherein a
hydrophilic membrane is used as a filtrating membrane for
the ultrafzltration in the re-use.
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(29) An ink-jet recordir~g medium comprising a
support and one or more iz~k-absorbing layezs provided on
the suppvzt, wherein at least one of the ink-absorbing
layers contains the porous substance according to tl2)_
(30) A coating la. quid far an ink-jet recazding
medium, containing the sol according to any one of (1) to
(11) .
Best Made for Carrying Out the Inventive
The present invention is described in detail
below.
The invention relates to a sol containing an
inorganic porous substance which has an average particle
diameter of 10 nm to 400 nm, as measured by the dynamic
light scattering method, an average aspect ratio of its
pzimary particles of 2 or more and meso--pores extending
in th.e longitudinal direction, and which suffers from
substantially no secondary aggregation.
fhe meso-pyres referred to in the invention means
fine pores of 2 to 50 nm, and the longitudinal direction
means the direction of a larger value between the average
paxticle diameter and average pazticle length of the
primary particles. The secondary aggregation referred to
in the invention means aggreg<~tion wherein the pximary
pazticles are connected and/or strongly aggregate one
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another and which cannot easily be dispersed into primary
particles_ The presence or absence of the secondary
aggregation can be judged by spraying a sufficiently
diluted sol and observing it on an electron microscope_
When the ratio of the number of primary particles/number
of total particles is 0_5 or more, it can be considered
that the particles suffer fre~tt substantially no secondary
aggregation_
The porous property referred to in the invention
means that pores can be measured by a nitrogen absorption
method and that the pore volume is preferably 0.1 ml/g or
more, mere preferably 0_5 ml/g or more. The average pore
diameter of the porous substance is not limited but is
preferably 6 nm or more, more preferably from 6 to 30 nrn,
further preferably from 6 to 18 nm_ Although it depends
on the intended applications, when the pare diameter is
large, large-sized substances can easily enter the pores
and diffusion is fast, thus being preferred. When the
poxes are small, moisture and the like in the air may
sometimes clog the pores to hinder the influx of
substances into the pores, thus being not preferred_ In
particular, when the sol is used as an ink-absorbing
layer of an ink-jet recording medium, an average pore
diameter of 6 to 18 nm which is near to the size of a
dyestuff is preferred so that the dyestuff in an ink is
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chemically held/stabilized, thereby an ink-absorbing
layer excellent in light resistance is obtained. The
substance having a uniform pore diamEter means a porous
substance wherein 500 or mere of the total pore volume is
included within the range of -~50a from the average pore
diameter, in terms of the total pore volume (volume of
poxes having a pore diameter of 50 nm or less measurable
by a nitrogen absorption method) and pore diameters
determined from a nitrogen absorption isothermal curvE.
Moreover, also by a TEM observation, it is possible t4
confirm that the fine pores are uniform.
The average particle diameter of the porous
substance of the invention measured by dynamic light
scattering method is preferably from 10 nm to 400 nm,
more preferably from 10 to 300 nm, further preferably
from 10 to 200 nm. In the case where the porous
substance zs dispersed in a solvent or a binder, a more
transparent product is obtained when the particle
diameter is 200 nm or less. In particular, when it is
used as an ink-absorbing layer of an ink-jet recording
medium, printed matter having good color-developing
property and a high color density is obtained owing to
the high transparency. When t'he diameter is larger than
200 nm, transpazency decreases, and when the diameter is
larger than 400 nm, the particles tend to precipitate at
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a high concentration of the sol, and hence both are not
preferred depending on the applications.
The average aspect ratio referred to in the
invention means a value obtained by dividing the larger
value by the smaller value between the average particle
diameter and average particle length of the primary
particles. The average particle diameter and the average
particle length of the primary particles can be easily
determined by electron microscopic observation. Azthough
a preferred aspect ratio varies in accordance with the
intended applications, particles having an average aspect
ratio of the primary particles of 2 or more can easily
hold a large amount of substances since packing of
particles is microscopically J_oose, as compared with
particles solely composed o~ particles having an average
aspect ratio of smaller than 2, and diffusion is also
fast, thus being preferred. Tn particular, when it is
used as an ink-absorbing layer of an ink-jet recording
medium, penetration of inks is improved. The average
aspect ratio is not limited a~~ far as it is 2 or more,
but the ratio of 5 or more is preferred in view of ink
absorbing property and glossiness. A shape may be any
shape such as fibrous, needle--like, rod~like, plate-like,
or cylindrical, but from the viewpoint of the ink
absorbing property, needle-like or rod-like is prefErred_
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xhe converted specific surface area SL (m'/g)
calculated from the average particle diameter DL (nm~
measured by dynamic light scattering method is determined
in accordance with an equation: SL = 6 x 7.03/(density
(g/cm3) x DL), assuming that the particles of a porous
substance are spherical_ xhe fact that the difference
between this tralue and the nitrogEn-absorption specific
surface area SB by the BET method, SB - SL, is 250 m2/g or
more means that particles of the porous substance are
highly porous. When the value is small, the ability to
absorb substances inside the substance decreases, and
hence, the ink-absorbing amount decreases in the case
where the particles are used as an ink-absorbing layer,
for example_ The value of Sa - SL is preferably 7.500 mz/g
ar less. When the value is large, the handling property
sometimes becomes worse_
A compound containing an organic chain may be
bonded to the porous substance of the invention. The
compound containing an organic chain includes a silane
coupling agent, an organic cationic polymer, and the like.
The addition of the silane coupling agent can
enhance bonding and adhesion to an organic medium.
Moreover, particles exceller~t in chemical resistance such
as alkali resistance care be obtained. Furthermore, a sol
which is stable even when subjected to acidification or
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addition of a cationic substance or an organic solvent,
and which is duxable to long-term storage can be produced.
The sil.ane coupling agent to be used is
preferably a compound represented by the following
general formula (2):
X"Si (OR) q_~ (2)
wherein X represents a hydrocarbon group having 1 to 12
carbon atoms, a hydz~ocarbon group having 1 to 12 carbon
atoms which is substituted by a quaternary ammonium group
and/or an amino group, or a group where hydrocarbon
groups having 1 to 12 carbon atoms which may be
substituted by a quaternary ammonium group and/or an
amino group are linked with one oz~ more nitrogen atoms, R
represents a hydrogen atom or a hydrocarbon group having
1 to 12 carbon atoms, az~d n is an integex of 1 to 3_
Specific examples of R include a methyl group, an
ethyl group, a propyl group, an isopropyl gxoup, a butyl
group, an isobutyl group, a tort-butyl group, a pentyl
group, an isopentyl group, a zxeopentyl group, a hexyl
group, an isohexyl group, a cyclohexyl group, a benzyl
group, and the like. Alkyl groups having Z to 3 carbon
atoms are preferred, and a methyl group and an ethyl
group are most preferred.
Moreover, among the groups of X, specific
examples of the hydrocarbon group having 1 to 12 carbon
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atoms include a methyl group, an ethyl group, a propyl
group, an isopropyl group, a butyl group, an isobutyl
group, a cyclohexyl group, a benzyl group, and the like.
A methyl group, an ethyl group, a propyl group, a butyl
group, a cyclohexyl group, and a benzyl group are
pxeferred_
Furthermore, among the groups of X, specific
examples of the hydrocarbon group having 1 to 12 carbon
atoms which is substituted by'a quaternary ammonium group
and/or an amino group includE an aminomethyl group, an
aminoethyl group, an amznopropyl group, an aminoisopropyl
group, an arninobutyl group, an aminoisobutyl group, an
aminocyclohexyl group, an aminobenzyl group, and the like.
An aminoethyl group, an aminopropyl group, an
aminocyclohexyl group, and an aminobenzyl group are
particularly prefierred.
In addztion, among the groups of X, the
hydrocarbon group having 1 to 12 carbon atoms zn the
group where hydrocarbon groups having 1 to 12 carbon
atoms which may be substituted by a quaternary ammonium
group and/or an amino group are linked with one or more
nitrogen atoms, is the same as above. the number of
nitrogen atoms linking the hydrpcarbon groups which may
be substituted by a quaternary ammonium group and/or an
amino group is prefErably from 1 td 4.
~s
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Specific examples of the compound represented by
the above general formula t2) include
methyltriethaxysilane, butyltrimethoxysilane,
dimethyldimethoxysilane, amznopropyltrimethoxysilane,
(aminoethyl)aminopropyltzzmethoxysilane,
aminopropyltriethoxysilane,
aminopropyldimethylethoxysilane,
aminopropylmethyldiethoxysilane,
aminobutyltriethoxysilane, 3-(N-stearylmethyl-2-
aminoethylamino)-propyltrimethoxysilane hydrochloride,
aminoethylaminomethylphenethyltrimethoxysilane, 3-[2-(2-
aminoethylaminoethylamino)propyl]trimethoxysilane, and
the like_
The additzon amount of the silane coupling agent
is preferably from 0_002 to 2, more preferably from 0.01
to 0.7 in terms of the weight ratio of the silane
couplzng agent/the porous substance. When the silane
coupling agent contains a nitrogen atom, the weight ratio
of the nitrogen atom in the dry weight of the porous
substance after treatment (hereinafter, xeferred to as
content) is preferably from 0.1 to 10a, more preferably
from 0_3 to 6ro. When the content is too low, it is
sometimes difficult to obtain the advantages of the
invention. When the content exceeds 10~, the product
sometimes lacks workability and other aptitudes for
16
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industrialization.
Fox the method of treatment with the silane
coupling agent, the agent znay be directly added to a sol
containing a porous substance. Alternatively, the agent
may be added aftez being dispersed in an. organic solvent
beforehand and hydrolyzed in the presence of water and a
catalyst. Fox the treating conditions, it is preferred
to conduct the treatment at a temperature of room
temperature to the boiling point of the hydrous
dispersion for several minutes to several days, more
preferably at a temperature of 25°C to 55°C for 2 minutes
to 5 hours.
The organic solvent could be alcohols, ketones,
ethers, esters, and the like_ Move specific examples
thereof to be used include alcohols such as methanol,
ethanol., propanol, and butanol, ketones such as methyl
ethyl ketone and methyl isobutyl ketone, glycol ethers
such as methyl cellosolve, ethyl cellosolve, and
propylene glycol monopropyl ether, glycols such as
ethylene glycol, propylene glycol, and hexylene glycol,
ester's such as methyl acetate, ethyl acetate, methyl
lactate, and ethyl lactate. The amount of the organic
solvent ~.s not particularly limited but the weight ratio
of the organic solvent/the szlane coupling agent is
preferably from 1 to 500, more preferably from S to 50_
7. '7
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For the catalyst, an inorganic acid such as
hydrochloric acid, nitric acid, or sulfuric acid, an
organic acid such as acetic acid, oxalic acid, or
toluenesulfoniC aczd, or a compound showing basic
property, such as ammonia, an amine, or an alkali metal
hydroxide can be used.
The amount of water necessary for the hydrolysis
of the above silane coupling agent is desirably an amount
so as to be from 0_5 to SO mol, preferably from 1 to 25
mol per mol of Si-OR group which constitutes the silane
coupling agent. Moreover, the catalyst is desirably
added so as to be from 0_Ol to 1 mol, preferably from
0.05 to 0.8 mol per mol of the silane coupling agent.
The hydrolysis of the above silane coupling agent
is conducted usually under an ordinary pressure at the
temperature of the boiling point of the solvent used or
lower, preferably at a temperature about 5 to 10°C lower
than the boiling point. When a heat-resistant pressure
vessel such as an autoclave is employed, it can be
conducted at a temperature higher than the above-
mentioned temperature.
Moreover, when the organic cationic polymer is
bonded to the porous substance of the invention, water
resistance and blur resistance are improved in the case
where it zs used as an ink-absorbing layer of an ink-jet
I8
CA 02471714 2004-06-23
recording medium. The organic cationic polymer to be
used can be optionally selected from among known organic
cationic polymers conventionally used fox ink-jet
recording media_
In the invention, the organic cationic polymer is
preferably a polymer having a quaternary ammonium salt
croup, particu~.arly preferably a homopolymer of a monomer
having a quaternary ammonium salt group or a copolymer of
tb.~.s monomer with one or more other monomers
copolymerizable therewith, and is particularly pre~srably
one having a weight-average molecular weight of 2,000 to
100, 000 _
The weight ratio o~ the orgazzic cationic polymer
to the porous substance torganic cationic polymer/porous
substance) is preferably in the range of 1/93 to 99/1.
More preferably, it is in the range of 10/90 to 90/I0.
To the porous substance of the in.ventic~n, a
hydrated metal oxide such as hydrated aluminum hydroxide,
hydrated zirconium hydroxide or hydrated tin hydroxide,
or a basic metal chloride such as baste aluminum chloride
can be added_ By adding the above compound, a~sol wh~.ch
is stable even when subjected to acidification, addition
of a cationic substance or an organic solvent or to
coxicentration, and which is durable to long--term storage
can be produced. .
J. 9
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The weight ratio of the above compound to the
porous substance (the above compound/porous substance) is
preferably in the range of 1/99 to 50/50. More
preferably, it is in the range of 5/95 to 30/70.
The zeta potential of the porous substance is
preferably +10 my or higher, or -10 mV or lower. When
the zeta potential of the particles is out of the above
range, electric repulsion between the particles reduces
and thereby dispersibility ber_omes worse and
precipitation and aggregation are apt to occur. The zeta
potential varies in accordance with pH. Although it
varies depending on the metal source and the solvent, a
sol which is stable even when subjected to addition of an
additive having an electric charge and which is durable
to long-term storage can be produced by utilizing surface
modification with a silane coupling agent or the like or
regulating pH.
By mixing a porous substance having positive zeta
potential and a poxous substance having negative zeta
potential, a porous substance which is connected in a
beads form and/or branched can be obtained. Although~it
depends on the intended application, particles connected
in a beads form and/or branched can easily hold a large
amount of substances since packing of particles is
microscopically loose and diffusion is also fast, thus
~0
CA 02471714 2004-06-23
being preferred. Tn particular, when it is used as an
a
ink-absorbing layer of an ink-jet recording medium, ink
penetration is improved.
Illustration is given below with reference to
examples_ An acidic aqueous solution of a porous
substance having negative zeta potential is slowly added
under stirring to an acidic aqueous solution of a porous
substance having positive zeta potential obtained by
surface modification with a silane coupling agent having
an amino group. The weight ratio of the porous substance
having negative zeta potential/the porous substance
having positive zeta potential is preferably from 0.001
to 0.2, more preferablx from 9.01 to o.OS_ When the
weight ratio zs 0.2 ox more, aggregation and
precipitation occur, and thus, this may sometimes be
undesixab~e.
xo the porous substance o~ the invention, a
calcium salt, a magnesium salt, or a mixture thereof can
be added. A porous substance which is connected in a
beads form and/or branched can be obtained also by the
addition of a calcium salt, a magnesium salt, or a
mixture thereof. In addition to the above effects, light
resistance may sometimes be improved with suppressing the
decomposition of a dyestuff in an ink, although the
detail is not clear.
21
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k'ox example. in the case where silica is selected
as the metal source, the calc~..um salt, magnesium salt, or
mixture thereof is preferably ;added in the form of an
aqueous solution. The amount of the e~lcium salt,
magnesium salt, or mixture thereof is prefex-ably 1500 ppm
or more, more preferably 1500 to 8500 pprn in terms of the
weight ratio of CaO. Mg0 or both of them relative to Si.02.
The addition is suitably carried out under stirring and
the mixing temperature and time are not particularly
limited but are preferably from 2 to 50°C and from 5 to 30
minutes_
Examples of the calcium salt and magnesium salt
to be added include inorganic. acid salts and organic ac~.d
salts such as chloride, bromide, fluoride, phosphate,
nitrate, sulfate, sulfamate, formate, and acetate of
calcium or magnesium. These calcium salts and magnesium
salts may be used as a mixture. The concentrat~.on of
these salts to be added is not particularly limited and
may be from about 2 to 20ro by caexght. When a multivalent
metal component other than calcium azzd magnesium is
contained in the above colloidal solution of silica
together with the calcium salt and magnesium salt, the
sol can be move preferably prc.~:~uced. Examples of the
multivalent metal component o~-her than calcium and
magnesium include divalent, trivalent, or tetravalent
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CA 02471714 2004-06-23
metals such as barium, zinc, titanium, strontium, iron,
nickel, and cobalt. The amount of the multivalent metal
components) is preferably from about 10 to 90a by weight
as multivalent metal oxides) relative '~o CaO, Mg0 and
the like when the amount of the calcium salt, magnesium
salt or the like to be added is converted into the amount
of CaO, Mg0 or the like.
It is sometimes desirable that the porous
substance of the invention does not contain sodium,
potassium, or a mixture thereof as far as possible.
Although it depezzds on the intended application, there
are cases where use at a high temperature may cause a
decrease in the amount of poxes or a change in the pore
diameter_
Far example, in the case where the porous
substance is silica, the amount of sodium, potassium, or
a mixture thereof is preferably 1000 ppm or less, more
preferably 200 ppm or less in teams of the weight ratio
of sodium, potassium or both of them to SiOz. Examples of
sodium and potassium to be contained include a metal and
inorganic acid salts and organic acid salts such as
chloride, bromide, fluoride, phosphate, nitrate, sulfate,
sulfamate, formate, and acetate of sodium or potassium.
The sol in, the iwsrention is a colloidal solution
wherein a liguid is used as a dispersing medium and the
2 ~3
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porous substance of the invention is a substrate to be
dispersed. The dispersing medium may be any as far as it
does not cause precipitation. Preferably, a solvent
selected from water, alcohols, glycols, ketones, and
amides ox a mixed solvent of two or mere of them may be
used. The organic solvent may be changed in accordance
with the intended application.. When accelerating the
drying rate of a coated film, it is preferred to use an
alcohol or a ketone which is low in latent heat of
vaporization as compared with water. The latent heat of
vaporization referred to herein means an energy amount
which is absorbed by a solveni= when it is vaporized.
Thus, low latent heat of vaporization means that the
solvent tends to vaporize. For the alcohols, lower
alcohols such as ethanol and methanol are preferred and
far the ketones, ethyl methyl ketone is preferred.
Moreover, when smoothness of a coated film is required,
solvents having a high-boiling point of 100°C or higher
are preferred, and particularly, ethylene glycol,
ethylene glycol monoprppyl ether, dimethylacetamide,
xylene, n-butanol, and methylene isobutyl ketone are
preferred.
Moreover, in order to prevent aggregation of the
particles, the sol preferab3y~ contains a stabilizer, e.g_,
an alkali metal hydroxide such as ATaOT-T, an organic base,
2. 9
CA 02471714 2004-06-23
NH40H, a low-molecular-,weight polyvinyl alcohol
(hereinafter referred to as PVA), or a surfactant.
particularly preferred is an alkali. metal hydroxide, NH40H,
or an organic base. When the stabilizer is added to the
sol, the porous substance is stable over a long period of
time without precipitation, gelation, and the like, and
hence, this case is preferred:. The amount of the
stabilizer to be added is preferably from 1 x l0'° to O.1S,
more preferably from 1 x 10-3 to 0_10, further preferably
from 5 x 10-3 to 0.05 as the weight ratio of the
stabilizer/the porous substance. When the amount of the
stabilizer is 1 x 10'4 or less, the charge repulsion of
the pozous substance becomes insufficient and hence long-
term stability is hardly maintained. Moreo~rer, when the
amount of the stabilizer is 0.15 or more, excessi~re
electrolyte is present, and gelation zs apt to pccur,
thus being not so preferred.
In order to regulate the ~riscosity of the sol, a
v~.scosity regulator may be incorporated. The viscosity
regulator means a substance capable of changing the
viscosity. For the viscos~.ty regulator, sodium salts,
ammonium salts, and the like are preferred. Particularly
preferred are one or more selected from NaZS03, Na2S09,
NaCl, and NH3HC03. The amount of the viscosity regulator
to be added is preferably from 5 x 10-S to 0_03, more
CA 02471714 2004-06-23
preferably from 1 x IO-° to 0.01, furthEr preferably from
x 10-' to S x l0-3 as the weight ratio of the viscosity
regulator/the porous substance. When the amount of the
viscosity regulator is 5 x 10-5 or less, the effect of
viscosity change is small, and when the amount of the
Viscosity regulator is 0.03 or more, excessive
electrolyte is present, and stozage stability i~
sometimes impaired, thus being not preferred.
The concentration of the sol varies in accordance
with the intended application, but is preferably from 0.5
to 30~ by weight, more preferably from 5 to 30o by weight.
Too low concentration is econ~>mically disadvantageous and,
in the case of using the sol for coating, the sol has a
defect that it is difficult to dry and also is not
preferred in View of transportation_ When the
concentration is too high, the viscosity increases and
there exists a possibility of dECreased stability, thus
being not preferred.
The gel of the invermion is preferably prepared
by a production process compri:;ing a step of mixing a
metal source comprising a metal oxide and/or its
precursor, with a template and water to produce a metal
oxide/template.complex, and a step of removing the
template from the complex.
The metal source for -use in the invention is a
26
CA 02471714 2004-06-23
metal oxide andlor its precursor and the metal species
include silicon, alkaline earth metals such as magnesium
and calcium and zinc belonging to Gxoup 2, aluminum,
gallium, rare earths and the like belonging to Group 3,
titanium, zirconium and the like belonging to Group 4,
phosphorus and vanadium belonging tv Group 5, manganese,
tellurium and the like belonging to Group 7, and iron,
cobalt and the like belonging to Group 8. The precursors
include inorganic salts such as nitrates and
hydrachlorides, organic salts such as acetates and
naphthenates, organometallic salts such as alkylaluminum,
alkoxides and hydroxides of these metals, but are not
limited thereto provided they can be synthesized by
synthetic methods described below. Of course, they may
be used singly or in combination.
In the case where silicon is selected as the
metal, a substance finally converted into silica by
repeated condensation and polymerization can be used as
the precursor and preferably, alkoxides such as
tetraethoxysilane, methyltriethoxysilane,
dimethyltriethoxysilane, and 1,2-
bis(triethoxysilyl)ethane, and active silica may be used
singly or in combination. Active silica is inexpensive
and highly safe and hence is particularly preferred.
Active silica fox use in the invention can be prepared by
2~
CA 02471714 2004-06-23
extraction from watez glass with an organic solvent or by
ion-exchange of water glass. For example, in the case of
the preparation by contact of water glass with a H''-type
nation exchanger, use of water glass No. 3 is
industrially preferred since it contains less Na and is
inexpensive_ xhe cation exchanger is preferably a
sul.fonated polystyrene-divinyl benzne-based strongly
acidic exck~.ange resin, e_g., Amberlite IR-120B
marzufactured by Rohm ~ Haas or the like but is not
particularly limited thereto. Moreover, at the time when
active silica is prepared, an alkali aluminate carp be
added to water glass_ Use of the resultirzg mixture of
silica and alumina enables the production without
precipitation even when the concentration is high. The
addition amount of the alka~.i aluminate is preferably
from 200 to 1500 as the elemental ratio of Si/A1 of the
mixture of silica and alumina. More preferably, the
amount is in the range of 300 to 1000. When the
elemental ratio of Si/Al is larger than 1500,
precipitation is apt to occur when the concentration is
increased. When the elemental ratio of Si/A1 is smaller
than 200, pores are sometimes not formed when the
template is removed.
Foz~ the alkali aluminate, sodium aluminate,
potassium aluminate, lithium aluminate, primary ammonium
:'3
CA 02471714 2004-06-23
aluminate, guanidine aluminate, and the like can be used,
and sodium aluminate is preferred. The elemental ratio
of Na/A1 in sodium aluminate zs preferably from 1.0 to
3Ø
The template for use in the invention may be any
cationic, anionic, nonionic and amphoteric surfactants
such as quaternary ammonium type, neutral templates such
as dodecylamine, tetradecylamine, hexadecylamine,
octadecylamine, and amine oxides. Preferably, nonionic
surfactants, e.g_, triblock-types such as Adeka Pluronic
L, P, ~', ~t series manufactured by Asahi Denka,
polyethylene glycols such as Adeka PEG sexies
manufactured by Asahi Denka, ethylenediamine-based types
such as Adeka Pluronic xR series can be used.
As the nonionic surfactant, there may be used a
triblock--type nonionic surfactant comprising ethy7.ene
oxides and propylene oxides represented by RO(C2Hap)~-
(C3H60)b-(C2Ha0)~R (wherein a and c each represent from 10
to 110, b represents from 30 to 70, and R represents a
hydrogen atom or an alkyl group having 1 to 12 carbon
atpms). In particular, preferred is a compound
represented by the structural formula: HO (CZH90) a- (C3H60) b--
(CzH40) ~H (wherein a and c ea~:h represent from 10 t4 7.10
and b represents from 30 to '7U) or a compound represented
by the structural formula: R(OCHZCHZ)"OH (wherein R
29
CA 02471714 2004-06-23
represents an alkyl group having 12 to 20 carbon atoms
and n represents from 2 to 30). Specifically, there is
Pluronie P103 (HO (C2H40) 1-r- (C3FIo0) so- (C2Ha0) I~I~) , P123
(Hp (CzHaO) 20- (C3H~0) ~o- (CZHQO) ZoH) , P85, and the like
manufactured by Asahi Denka, and polyoxyethylene lauryl
ether, polyoxyethylene cetyl ether, polyoxyethylene
stearyl ether, and the like.
For the purpose of changing pore diameter, an
aromatic hydrocarbon having 6 to 20 carbon atoms, an
alicyclic hydrocarbon having 5 to 20 carbon atoms, an
aliphatic hydrocarbon having 3 to 16 carbon atoms, and
amine and halogen-substituted derivatives thereof, e.g.,
toluene, trirnethylbenzene, tr_iisc~propylbenzene, and the
like may be added.
7Che production process of the invention is
described below.
The reaction of the metal source with the
template can be carried out after mixing a solution Qr
dispexszon of the metal source in a solvent with a
solution or dispersion of the template in a solvent urxder
stirring, but is not limited thereto. For the solvent,
either water or a mixed solvetzt of water and an organic
solvent may be used. For the organic solvent, alcohols
are preferred. For the alcohols, lower alcohols such as
ethanol and methanol axe preferred.
CA 02471714 2004-06-23
A composition for use in the reaction varies
depending on the template, metal source and solvent, but
it is necessary to select a range of the composition
which does not cause aggregation and precipitation of the
particles leading to enlargement of particle diameter.
Moreover, in order to prevent the aggregation and
precipitation of the particles, a stabiliser, e.g., an
alkali such as NaOH or low-molecular-weight PVA may be
incorporated. In addition, a pH regulator, a metal
sequestering agent, a fungicide, a surface-tension
regulator, a wetting agent, and an antirust agent may be
added into the sowent in a range where aggregation and
precipitation do not occur.
For example, when active silica is used as the
metal source, Pluronic P123 is used as the template, and
water is used as the solvent, the following composition
may be employed. The weight ratio of P123/Si02 to be used
is in the range of preferably 0.01 to 30, more preferably
0.1 to 5. The weight ratio of an organic auxiliary/Plz3
is preferably from 0.02 to 100, more preferably 0.05 to
35. The weight ratio of water/P123 to be used at the
reaction is in the range of preferably 10 to 1000, more
preferably 20 to 500. As a stabilizer, NaOH may be added
in the range of 1 x 10-' to 0.15 as the weight ratio of
NaQH/Si02. zn the Case of using Pluronic P103, the same
31
CA 02471714 2004-06-23
composition may be used.
Mixing of the metal source, the template and the
solvent is conducted preferably at 0 to 80°C, more
preferably at 0 to 40°c under stirring.
The addition period in the invention means a
period of time required for the addition of the metal
source to the template solution or the addition of the
template solution to the metal source from the start to
the completion.
The addition period is preferably 3 minutes or
more, more preferably 5 minutes or more. When the
addition period is less than 3 minutes, the average
aspect ratio of the primary particles becomes less than 2,
and in the case where they are used as the ink-absorbing
layer of an ink-jet recording medium, an ink-absorbing
amount sometimes decreases_
The addition period can be controllEd by the
addition rate of the metal source or the template
solution. A substantially constant addition rate is
preferred since reproducibility of the average aspect
ratio~and average particle diameter of the primary
particles are satisfactory, but the rate is not
necessarily constant.
The reaction easily proceeds even at an ordinary
temperature, but may be carried out under heating up to
32
CA 02471714 2004-06-23
100°C, if necessary. However, the condition such as a
hydrothermal reaction at 100°C or higher is not necessary.
The reaction pexiod to be used is in the range of
0_5 to 100 hours, preferably 3 to 50 hours. The pH upon
the reaction is in the range of preferably 3 to 12, more
preferably 6 to 11, further preferably 7 to 10. For
example, silicon is selected as the metal, regulation of
pH to 7 to 10 may sometimes shorten the reaction period.
For the purpose of regulating the pH, an alkali such as
NaOH or ammonia or an acid such as hydrochloric acid,
acetic acid, or sulfuric acid may be added.
At the time when the sol of the porous substance
is produced, an alkali aluminate can be added and the
timing may be before and after the formation of the
complex and after the removal of the template.
When the complex contains silicon, a sol stable
even when it zs acidified or a catzonic substance is
added and durable to long-term storage can be produced by
adding the alkali aluminate_
As the alkali aluzninate to be used, sodium
aluminate, potassium aluminate, lithium aluminate,
primary ammonium alurninate, guanidine aluminate, and the
like can be used, and sodium aluminate is preferred. The
elemental ratio of Na/A1 in sodium aluminate is
preferably from 1_0 to 3.0_
3 ~3
CA 02471714 2004-06-23
Illustration is given below with reference to the
case where the alkali aluminate is added after the
removal of the template as an example. A solution of the
alkali aluminate is added under stirring at a temperature
of 0 to 80°C, preferably 5 to 40°C_ The concentration of
the alkali aluminate to be added is not particularly
limited but is preferably from 0.5 to 90a by weight, more
preferably 1 to 24~ by weight. For example, in the case
where the porous substance contains silicon, the addition
amount is preferably from 0_003 to 0.1, more preferably
0_005 to 0.05 zn terms of the elemental ratio of
Al/(Si+~1). After the addition, heating at 40 to 95°C is
preferred and heating at 60 to 80°C is more preferred.
The method for removing the template is described
below. For example, the porous substance may be obtained
by filtering off the resulting complex by filtration or
the like, followed by washing with water, drying, and
removal of the template contained therein by a method of
bringing it into contact with a supercritical fluid or a
solvent such as an alcohol, or by baking. The baking
temperature is higher than the temperature at which the
template disappears, e_g_, higher than about 500°C. The
baking period is suitably determined in accordance with
the temperature, but is firom about 30 minutes to 6 hours.
Far other methods of removal, a method of mixing a
34
CA 02471714 2004-06-23
solvent and the complex under stirring, a method of
flowing a solvent through a column packed with the
complEx, or the like may be applied.
Moreover, a porous substance is obtained by
adding a solvent such as an alcohol to the resulting
xeaction solution and removing the template from the
complex. At this time, when an ultrafiltration apparatus
is used, the porous substance can be handled .in. the form
of a sod., and hence, it is preferred. xhe
ultrafiltration may be conducted under either an elevated
pressuxe or a reduced pressurra as well as under an
atmospheric pressure. As a mate.rzal of the membrane for
ultrafiltration, polystyrene, polyether ketone,
polyacrylonitrile (PAN), polyn.lefins, cellulose, and the
like can be employed_ The form may be any of a hollow
fiber type, a flat membrane type, a spiral type, a tube
type, and the like. The matexzal of the membrane for the
ultrafil.tratxon is preferably a hydrophilic membrane such
as a P.AN membrane, a cellulose membrane, or a charged
membrane.
The charged membrane includes a positively
charged membrane and a negatively charged membrane. The
positively charged membrane ixicludes membranes wherein a
positive change group such as a quaternary ammonium salt
group is introduced into organic polymers such as
CA 02471714 2004-06-23
polysulfones, polyether sulfones, polyarnide and
polyolefins and inorganic substances, and the negatively
charged membrane includes membranes wherein a negative
charge group such as a carboxyl group or a sulfonic acid
group is introduced into organic polymers and inorganic
substances_
At the ultrafiltration, a stabilizer, e.g., an
alkali such as NaOH or low-molecular--weight PVA may be
added in order to prevent aggregation of particles and
also a viscosity regulator, e.g., a sodium salt such as
Na2S03 or an ammonium salt such as NH3HC03 may be added.
The solvent used for the removal may be any solvent as
long as it dissolves the template, and may be water which
is easy to handle or an organic solvent having a high
dissolving power.
T1-~e template is preferably removed at a pH of the
sol irz the range of preferably 7 to 12, more preferably 8
to 11. For the purpose of regulating the pH, an alkali
such as NaOH or ammonia or an acid such as hydrochloric
acid, acetic acid, or sulfuric acid may be added. When
the pH is too high, there is a possibility of altering
the structufie of the porous substance and when the pH is
too low, there is a possibility of aggregation, thus
being not so preferred.
The temperature for the removal is preferably a
3 Fi
CA 02471714 2004-06-23
cooled temperature which is equal to or lower than the
micelle-forming temperature of the template. By cooling
the sol to a temperature which is equal to or lower than
the micelle-foaming temperature, the template is
dissociated and thereby the sol becomes easy to pass
through a filtration membrane. The micelleJforming
temperature herein means a temperature at which the
template begins to form micelles in a solution when a
temperature is elevated at any concentration. Actually,
the temperature varies in accordance with the solvent or
temperature to be used, but is preferably 60°C or lower,
more preferably from 0 to 20°G. When the temperature is
too low, the solvent may freeze, thus being not preferred.
When the porous substance is a metal oxide and
the above silane coupling agent is added to the resulting
reaction solution, a hydroxyl group on the surface reacts
with the silane coupling agent and thereby the template
is liberated from the complex. When the pH is regulated
to around isoelectric point (pH whose absolute difference
from the isoelectric point is within 1_5), electric
repulsion between the particles decreases, and thus, the
porous substance aggregates, so that the template can be
easily removed by centrifugation, filtration, or the like.
After the removal of the template, when the pH is
regulated to a pH which is apart from the isoelectric
~7
CA 02471714 2004-06-23
point, there is obtained a porous Substance having an
average partzcJ.e diameter of 10 to 400 nm and suffering
from substar~tzally no secondary aggregation.
The template thus removed can be z~e-used after
the removal of the solvent. As compared with the removal.
by incineration, the re--use can industrially suppress a
raw material cost. Moreover, since there is no
generation of heat by the incineration and no wasteful
spending of resources, it is suitable for solving an
environmental problem. As a method for the re-use, any
method may be employed as far as it, does not decompose
the template. For example, the template solution removed
by ultrafiltration or the like is heated to the micelle
temperature or highex, and the template may be
concentrated using an ultrafiltration membrane having a
small fractionation molecular weight, and then used. The
ultrafiltration membrane to be used at this time is
preferably a hydrophilic membrane. Moreover, the solvent
may be removed by dzstillation-
For concentrating the sol, when viscosity of the
sol is high, for example, distillation is more efficient
and preferred than the use ofi ultrafiltration. The
distillation may be conducted by any method unless it
izxduces precipitation or gelai:ion, but from the
viewpoints of sol stability and distillation efficiency,
CA 02471714 2004-06-23
distillation undex reduced pressure is preferred. The
heating temperature at the distillation is preferably
from 20 to 100°C, more preferably fxom 20 to 45°C. As the
method for concentration, use of a method of
concentration while always maintaining the liquid surface
at a constant level by newly adding the porous substance
sol in an amount corresponding to a vaporized solvent is
preferred since drying of the sol in the vicinity of the
liquid surface can be prevented. For example, a rotary
filter, a rotary evaporator, a thin~film evaporation
apparatus, and the like can be employed. The
concentration by the distillation method may be conducted
singly or in combination with ultrafiltration. In the
case where ultxafiltration is used in combination,
distillation may be carried out before and/or after
ultrafiltration, but it is preferred to carry out
distillation after ultrafiltration in view of an
advantage that the solvent to be vaporized decreases.
Moreover, before distillation, in order to reduce the
risk of precipitation and gelation, it is preferred to
add a stabilizer or to treat the porous substance with a
silane coupling agent or the like.
~s a method of obtaining the porous substance by
removing the solvent fxom the sol, methods of drying by
heating, vacuum drying, spray-drying, supercritical
39
CA 02471714 2004-06-23
drying, and the like can be employed.
The porous substance and/or sol of the porous
substance of the invention may be variously modified in
accordance with the intended application. Fox example, a
metal such as platinum or palladium may be supported
thereon.
xhe coexistence of silica such as colloidal
silica in the sol of the porous substance allows the
solid mass concentration in the sol to increase and hence
is preferred. Moreover, when the silica-coexisting
liquid is applied to form a coated film, film thickness
and film strength can be improved as compared with the
case where the sol is applied solely, thus being
preferred.
Since the porous substance of the invention has
pores, an effect of absorption of substances inside, an
effect of protection by inclusion, and an effect of
sustained release are expected. For example, it can be
employed as an adsorbent for an adsorption heat pump, a
humidity-controlling agent, a catalyst, a catalyst
support, an ink absorber, a drug carrier for use in a
drug delivery system, a carrier far cosmetics, foods,
dyes, and the like. Also, since it is a fine particulate,
it is possible to apply it to fields requiring
transparency, smoothness, and the like_ For example, it
CA 02471714 2004-06-23
can be used as a filler for rubbers, resins and paper, a
thickening agent for paints, a thixotropy agent, a
precipitation-preventing agent, an antiblocking agent for
films, and the like. Furthermore, since it is
transparent, has pores and zs low in density, it can be
also used as a low-refractive index film, an
antireflection film, a low-dielectric constant film, a
hard-coated film, a heat-insulating material, a sound
insulating material, and the like. 2n particular,
utilizing a capability of forming a transparent and
smooth film and an effect of absorbing substances by the
poxes, it can be suitably used for photographic-like ink-
jet recording media_
Use as an ink-jet recording medium is described
below. As an ink fox use in ink-jet recording, a
dyestuff may be either a dye or a pigment, and a solvent
may be either aqueous or nonaqueous.
In the invention, the ink-jet recording medium is
constituted by a support and one or more ink-absorbing
layers provided on the support. It necessary, two or
more ink-absorbing layers may be provided_ Thus, by
making the ink-absorbing layer a multilayer structure,
Functions such as imparting glossiness on the surface can
be assigned to respective layers. The porous substance
of the invention should be contained in at least one
91
CA 02471714 2004-06-23
layer.
The content of the porous substance of the
invention is not particularly limited but is preferably
contained in an amount of 10 to 9~S by weight per each
ink-absorbir~g layer containing the porous substance.
Moreover, an amount of 1 to 99~ by weight relat~.ve to the
total ink-absorbing layers is preferred_ A low content
is not preferred since ink absorbing property decz~eases.
In the ink-absorbing layer of the invention, an
organic binder can be employed as a binder which does not
impair the ink absorbing property of the above porous
substance. Examples thereof include polyvinyl alcohol
(hereinafter referred to as PVA) and its dezivatives,
polyvinyl acetates, po7.yvinyl pyrrol.idones, polyacetals,
polyurethanes, po~.yvinyl butyrals, pozy(meth)acrylic acid
(estersa, polyamides, polyacrylamides, polyester resins,
urea resins, melamine resins, starch and starch
derivatives originated from a natural polymer, cellulose
derivatives such as carboxymethyl Cellulose and
hydroxyethyl cellulose, casein, gelatin, latexes,
emulsions, and the like. Examples of the latexes include
a vinyl acetate polymer latex, a styrene~isoprene
copolymer latex. a styrene,butadiene copolymer latex, a
methyl methacrylate-butadiene copolymer latex, an acrylic
ester copolymer latex, functional group-modified polymer
42
CA 02471714 2004-06-23
latexes obtained by modifying these copolymers with a
monomer containing a functional group such as a carboxyl
group, and the like. examples of the PVA derivatives
include cation-modified polyvinyl alcohol, silanol-
modified polyvinyl alcohol, and the like. Of course,
these binders can be used in combination.
The content of the organic binder for use in the
invention is not particularly limited, but in the case of
using polyvinyl alcohols, for example, it is preferred to
be contained in an amount of 5 to 400 parts by weight and
it is particularly preferred to be contained in an amount
of 5 to 100 parts by weight per 100 parts by weight of
the porous substance. When the content is small, a film-
forming property deteriorates and when it is large, ink
absorbing property decreases, thus both being not
preferred.
The invention also provides a coating liquid for
an ink-jet recording medium comprising ink-absorbing
layer-constituting components and a solvent. xhe solvent
to be used is not particularly limited, but a water-
soluble solvent such as an alcohol, a ketone, Qr an ester
and/or water are preferably used. Furthermore, in the
coating liquid, a pigment-dispersing agent, a thickening
agent, a flow regulator, an antifoaming agent, a ~oam~
suppressing agent, a releasing agent, a foaming agent, a
43
CA 02471714 2004-06-23
colorant, and the like can be blended_
In the invention, at Zeast one ink~absorbing
layer preferably contains a cationic polymer. Water
resistance at printed parts is improved by incorporation
of the cationic polymer. The cationzc polymer is not
particularly limited as far as it exhibits a cationic
property, but preferably used are those containing at
least one of primary amine, secondary amine and tertiary
amine substituents and salts thereof or at J.east one of
quaternary ammonium salt substituents. Examples thereof
include dimethyldiallylammonium ch3.oride polymers,
dimethyldiallylammanium chloride-acrylamide copolymers,
alkylarnine polymers, polyaminedzcyan polymers,
polyallylaznine hydrochlorides, and the like. The
molecular weight of the cationic polymer is not
particularly lzmited but these having a weight-average
molecular weight of 1,000 to 200,000 are preferably used.
In the invention, at least one ink-absorbing
J.ayer preferably contains a U"Lr absorbent, a hindered
amine-based light stabilizer, a slnglet oxygen quencher,
and an antioxidant. Light resistance in printed parts is
improved by ~.ncorporation of the substances. The UV
absorbent is not particularly J.zmited but benzotrxazoles,
benzophenones, titanium oxide, cerium oxide, zinc oxide,
and the like are preferably used. The hinderEd amizze-
~~ 4
CA 02471714 2004-06-23
based light stabilizer is not particularly limited but
those wherein the N atom in the piperidine ring is
represented by N-R (wherein R is a hydrogen atom, an
alkyl group, a benzyl group, an allyl group, an acetyl
group, an alkoxyl group, a cyclohexyl group, ar a
benzyloxy group) axe prEferably employed. The singlet
oxygen quencher is not particularly limited, but aniline
derivatives, organonickels, spirochromans, and
spiroindanes are preferably used. The antioxidant is not
particularly limited, but phenols, hydroquinones,
organosulfurs, phosphorus compounds, and amines are
preferably employed.
In the invention, at least one ink-absorbing
layer preferably contains an alkaline earth metal
compound. Light resistance is improved by incorporation
of the alkaline earth metal compound. As the alkaline
earth metal compound, oxides, halides and hydroxides of
magnesium, calcium, and barium are preferably used. A
method for incorporating the alkaline earth metal
compound into the ink-absorbing layer is not particularly
limzted. The compound may be added to a coating liquid
slurry or may be added and adhered during or after the
synthesis of an inorganic porous substance and then used.
The amount of the alkaline earth metal compound to be
used is preferably from 0.5 to 20 parts by weight in
CA 02471714 2004-06-23
terms of the oxide per 100 parts by weight of the
inorganic porous substance.
In the invention, at least one xnk-absorbing
layer preferably contains a nonionic surfactant. Image
quality and light resistance are improved by
incorporation of the nonionic surfactant. The nonionic
surfactant i$ not particularly limited, but higher
alcohols, ethylene oxide adducts of carboxylic acids, and
ethylene oxide-propylene oxide copolymers are preferably
used, and ethylene oxide-propylene oxide copolymers axe
more preferably used. The method for incorporating the
nonionic surfactant into the ink-absorbing layer is not
particularly limited. The surfactant may be added to a
coating liquid slurry or may be added and adhered during
ox after the synthesis of an inorganic porous substance
and then used.
Tn the invention, at least one ink-absorbing
layer preferably contains an alcohol compound. Tmage
quality and light resistance are improved by
incorporation of the alcohol compound. The alcohol
compound is not particularly limited, but aliphatic
alcohols, aromatic alcohols, polyhydric alcohols, arid
oligomers containing a hydroxyl group are preferably used,
and polyhydric alcohols are more preferably used. The
method for incorporating the alcohol Compound into the
46
CA 02471714 2004-06-23
ink-absorbing layer is not particularly limited. The
alcohol compound may be added to a coating liquid slurry
or may be added and adhered during ar after the synthesis
of an inorganic porous substance and then used.
In the invention, at least ane ink-absorbing
layer preferably contains an alumina hydrate. Image
quality and water resistance are improved by
incorporation of the alumina hydrate_ The alumina
hydrate is not particularly limited, but alurnina hydrates
having a boehmite structure, pseudo-boehmite structure,
or amorphous structure are used, and alumina hydrates
having a pseudo-boehmite structure are preferably used.
zn the invention, at least one ink-absorbing
layer preferably contains colloidal silica and/or dry
process silica. Image quality is improved and glossiness
can be imparted by incorporation of colloidal silica
and/or dry process sllica_ The colloidal silica is not
particularly limited, but a usual anionic colloidal
silica and a cationic colloidal silica obtained by a
method of the reaction with a multivalent metal compound
such as aluminum ion are used. The dry process silica is
not particularly limited but a vapor-phase process silica
synthesized by burning silicon tEtrachloride with
hydrogen and oxygen is preferably used.
The dry process silica may be used as it is or
97
CA 02471714 2004-06-23
may be one whose surface is modified with a silane~
coupling agent or the like.
In the invention, a glossy layer can be provided
on the outermost layer_ The means for providing the
glossy layer is not particularly limited, but a method of
incorporating a pigment having an ultxafine particle
diameter such as colloidal silica and/or dry silica, a
super calendar process, a gloss calendar process, a cast
process, and the like may be employed.
xhe suppoxt to be used in the invention is not
particularly limited, but a paper, a polymer sheet. a
polymer Pilm, or a cloth is preferably used. These
supports can be subjected to surface treatment such as
corona discharge, if necessary. The thickness of the
ink-absorbing layex is not particularly limited but is
preferably.from 1 to 100 ~m and the coating amount is
preferably from 1 to 100 glrnZ. The method for applying
the coating liquid is not particularly limited, but a
blade coater, an air-knife coater, a roll coater, a bxush
coater, a curtain coater, a bar coater, a gravure coater,
a spray, and the like may be used.
examples
The present invention will be illustrated in
gxeater detain with reference to the following Examples.
48
CA 02471714 2004-06-23
The pore distribution and specific surface area
were measured with nitrogen using AUTOSORB-1 manufactured
by Quantachzome. the pore distribution was calculated by
the BJH method. The average pore diameter was calculated
from the values of peaks in the meso-pore region of a
differential pore distribution curve determined by the
B3H method. The specific surface area was calculated by
the BEx method.
The average particle diameter according to
dynamic light scattering method was measured on a laser
zeta~potential electrometer ELS-800 manufactured by
Otsuka Electronics Co., Ztd_
The viscosity was measured at a temperature of
25°C on a viscometer LVDVZI~ manufactured by Brookfield
using a spindle No. 21 dedicated to a small~amount sample.
A TEM photograph was taken using H-7100
manufactured by Hitachi.
A coating film was obtained by coating a
transparent PET film (LUmirrar Q80D manufactured by Toray
Industries, Inc.) with a coating liquid prepared in a
ratio of a porous substance: PVA-127 (manufactured by
Kuraray Co., Ltd.): PVA-82130 (manufactured by Kuraray
Co., Ltd.) - 100:10:20 (solid mass ratio).
As a method for measuring film thickness, a film
was foamed using a bar caater and then the thickness was
49
CA 02471714 2004-06-23
measured at 10 points in a central part excluding the
parts within 3 cm from upper and lower edges by means of
a micromEter_ The film thickness was calculated as an
average thereof.
As a means for measuring film strength, pencil
strength was employed. That is, in accordance with
pencil stxength test (JIS K-5900), a film was scratched
with the lead of a pencil and the presence of a break was
investigated. A pencil density symbol (68 to 9H) one-
rank lower than the symbol of the pencil with which the
break was observed was determined as the pencil strength.
Printing characteristics were evaluated by solid-
printing on the above coating film with yelZvw, magenta,
cyan and black inks using a commercially available ink-
jet printer (PM-800C manufactured by Seiko Epson
Cvrporation)_ Ink absorbing property was judged based on
presence of blur after printing and a degree of ink
transcription when a printed part was pressed with a
white paper immediately after printing.
G: Good, H: Bad
Water resistance was evaluated by dropping one
drop of pure water onto a printed part of the above
coating film and was judged by degrees of blur and
effusion after drying.
G. Good, F: Slightly good, B. Bad
JO
CA 02471714 2004-06-23
Light resistance was evaluated by irradiating the
printed coating film using a Xenon Fade-Ometer Ci-3000F
(manufactured by Toyo Seiki) under conditions of an S-
type polysiZicate irzner filter, a soda lime outer filter,
a temperature of 24°C, a humidity of 60~RH, and a
radiation intensity of 0.80 W/m2_ Optical density of each
color before and after 60 hours of irradiation was
measured and a chang~.ng rate of the density was
determined_ The optical density was measured using a
reflection densitometer (RD-91.8 manufactured by Gretag
Macbeth).
G: Good, F: Slightly good, B: Bad
Evaluation results of coating films and sols in
the following examples are shown in Tables 1 arid 2.
Examp~.e 1
Into a dispersion of 1000 g of a canon-exchange
resin (Amberlite, IR-~120B) convErted to Ht-type beforehand
in 1000 g of water was added a solution of 333.3 g of
water glass No_ 3 (Si02 = 29$ by weight, Na20 = 9.5b by
weight) 'diluted with 666. g of water. After the mixture
was thoroughly stirred, the cation-exchange resin was
filtered off to obtain 2000 ci of an active silica aqueous
solution. The Si02 concentra:.ion of the active silica
aqueous solution was 5.Oro by weight.
CA 02471714 2004-06-23
In 8700 g of water was dissolved 100 g of
Pluronic P123, and 1200 g of the above active silica
aqueous solution was added thereto at a constant z~ate
over a period of 10 minutes under stirring in a water
bath at 35°C. The pH of the mixture was 4Ø At this
time, the weight ratio of water/QZ23 was 98.4 and the
weight ratio of P123/Si02 was 1.67. After the mixture was
stirred at 35°C for 15 minutes, it was al7.owed to stand at
95°C and the reaction was effected for 29 hours. Ethanol
and an Na~H aqueous solution v~~ere added to the resulting
reaction solution so that the weight ratio of
water/ethanol became 1/0.79 and the weight ratio of
NaOH/Si02 became 0.045/1 after_ the addition. The pH of
the solution was 9_0. The solution was subjected to
filtration using a PRN membrane AHP-007.3 manufactured by
Asahi Kasei Corporation as an ultrafiltration membrane
and thereby the zxonionic surfactant P123 was removed to
obtain a transparent sol (A) of a porous substance having
an Si02 concentration of 7_Oa by weight. The pH was 10.0
and the zeta potential was -45 mV. The viscosity of the
sol (A) was 360~cP_
The average particle diameter of the sample in
the sol (A.) measured by dynamic light scattering method
was 200 nm and the converted specific surface area was
13_6 m2/g. The sol was dried at 3.05°C to obtain a porous
52
CA 02471714 2004-06-23
substance. The average pore diameter of the sample was
nm and the pore volume was 1.11 ml/g. xhe nitrogen-
absorption specific surface area by the SET method was
540 m2/g and the difference from the converted specific
surface area was 526.4 mz/g. When observed by an electron
microscopic photography, primary particles of the sample
were found to be rod-like particles having an average
particle diameter of 30 nm and an average particle le~zgth
of 200 nm and having an average aspect ratio of 6.7.
When the resulting sol was transformed into a
coating film, it dazed at room temperature within about
10 minutes to afford a fzJ.m having a film thickness of
18 _ 0-1-2 _ 0 ~.m and a pencil strength of HB.
E~cample 2
To the mixture of Sa_OZ and P123 obtained in
Example 1 was added a 0_1N Na4~ aqueous solutzon, whereby
the pH was regulated to 9.5_ :after 3 hours of a xeaction
under stirring at 65°C, the same operations as in Example
1 afforded a product equal to the sol (A).
Example 3
To 100 q of the sol (A) obta~.ned in Example Z was
added 0_41 g of a 10$ by weight calcium nitrate aqueous
solution at room temperature under stirring. The pII
~'~ 3
CA 02471714 2004-06-23
after 30 minutes of stirring at room temperature was 9.9.
When observed by an electron microscopic photography, a
primary particle of the sample comprised rod-like
particles having an average particle diameter of 30 nm
and an average paxticle length of 200 nm, about 10 pieces
o~ the particles being connected in a beads form. The
resulting sol (B) was transformed into a coating film_
Example 4
To 100 g of the sol (~) obtained in Example i was
added 0.99 g of a 10~ by weight magnesium chloride
aqueous solution at room temperature under stirring_ The
pH after 30 minutes of stirring at room temperature was
9.8. When observed by electron microscopic photography,
a primary paxticle of the sample comprised rod-like
particles having an average particle diameter of 30 nm
and an average particle length of 200 nm, about 10 pieces
of the particles being connected in a beads form. The
resulting sol (C) was transformed into a coating film.
Example S
To 100 g of the sol (A) obtained xn Example 1 was
added 0.51 g of 3-(2-
aminoethyl)amznopropyltrimethoxysilane_ Aftex the whole
was sufficiently stirred, 1_~~6 g of 6N hydrochloric acid
54
CA 02471714 2004-06-23
was added thereto. A clumpy aggregate was once formed
but when it was dispersed using an ultrasonic dispersing
machine, a sol (D} was obtained. The pH was 2.1 and the
zeta potential was -34 rnV. The resulting sol (D) was
transformed into a coating film.
Example 6
To the sol (D) obtained in Example 5 was added a
6N sodium hydroxide solution to regulate the pH to 10_0.
A dumpy aggregate was once formed but when it
was dispersed using an ultrasonic dispersing machine, a
sol (E) was obtained. The zeta potential was -45 mV.
The resulting sol (E) was transformed into a coating film.
Example 7
To 100 g of the sol (A) obtained in Example 1 was
added 2_14 g of a 40~ methanol solution of 3-(N-
styrylmethyl-2-aminoethylamino)propyltrimethoxysilane
hydrochloride. After the whole was sufficiently stirred,
3_57 g of 6N hydrochloric acid was added thereto. A
cZumpy aggregate was once formed but when it was
dispersed using an ultrasonic dispersing machine, a sol
(F) was obtained. The pH was 1.1 and the zeta potential
was -38 mV. The resulting sol (F) was transformed into a
coating film.
CA 02471714 2004-06-23
Example 8
To 100 g of the sol (D) obtained in Example 5 was
slowly added 3.0 g of the sol (R) obtained in Example 1
under stirring. The pH was 2.5. When observed by an
electron microscopic photography, a primary particle of
the sample comprised rod-like particles having an average
particle diameter of 30 nm and an average particle length
of 200 nm, about 15 pieces of the particles on average
being connected in a beads form. The resulting sol (G)
was transformed into a coating film_
Example 9
To 100 g of the sol (D) obtained in Example 5 was
added 7 g of a 10o by weight aqueous solution of
diallyldimethylammanium chloride having a molecular
weight of about 40,000 as a ration polymer at room
temperature under stirring_ xhe whole was dispersed
using an ultrasonic dispersing machine to obtain a sol
(H). The pH was 2_2. The resulting sol (H) was
transformed into a coating film.
Example 10
To 100 g of the sol (~) obtained in Example 1 was
added 6.1 g of PAO #3S (basic aluminum chloride solution)
56
CA 02471714 2004-06-23
manufactured by Asada Chemical Industry Co., Ltd_ at room
temperature under stirring. After 10 g of a cation-
exchange resin (Amberlite, zR--120B) converted td H+-type
beforehand was added and the whole was sufficiently
stirred, the canon-exchange resin was fiJ.tered off_ The
pH was 3_0 arid the zeta potential was ~36 mV. The
resulting sot (I) was transformed into a coating fzlm.
Example 11
To 200 g of the sot (A) obtained in Example Z was
mixed 10 g of commercially available colloidal silica
(5nowtex N manufactured by Nissan. Chemical Industries,
Ltd_) to obtain a sol (J). When the resulting soJ. (J)
was trarzsformed into a coating film, i.t dried at zoom
temperature withzn about 10 minutes to affoz~d a film
having a film thickness of J.8 . 0~1 _ 5 dun az~d a pencil.
strength of H_
Example 12
Ethylene glycol was added to the sol (A) obtained
in Example 1 so that it was contained in an amount of 10~
in the soJ.vent, and thereby a sol (K) was obtained_ The
viscosity of the solution was 450 cP_ When the sol (FC)
was transformed into a coating film, it dried at room
temperature within about 120 minutes to afford a film
57
CA 02471714 2004-06-23
having a film thickness of 20.010_5 ~m and a pencil
strength of HB.
Example 13
To 200 g (viscosity 350 c~) of the sol (A)
obtained in Example 1 was added 2 g of a 10~ by weight
NaZS03 aqueous solution and the whole was stirred for
about 10 minutes to obtain a sol (J)_ xhe viscosity of
the resulting sol (L) was 10 cP. When the sol (L) was
transformed into a coating fzlm, it dried at room
temperature within about 10 minutes to afford a film
having a film thickness of 17.0~1.5 dun and a pencil
strength of HB_
Example 14
An NaOH aqueous solution was added to the
reaction solution obtained in Bxample 1 so that the
weight ratio of NaOH/Si02 became 0.045. After coolzng to
10°C, the Pluronic was extracted using AHP-1010 as an
ultrafiltration membrane to obtain a sol (M) having a
silica concentration of 7_2b by weight. In the membrane
employed at this time, slight clogging was observed.
ThE average paxticle diametez of the sample in
the sol (M), measured by dynamic light scattering method,
was 200 nm and the converted specific surface area was
J~
CA 02471714 2004-06-23
x.3.6 mz/g. The sol was dried at 105°C to obtain a porous
substance. The average pore diameter of the sample was
nm and the pore volume was 1.10 ml/g. The nztrogen-
absorption specific surface area by the BET method was
535 m2/g anal the difference from the converted specific
surface area was 521_4 mz/g. When obser~cred by an electron
microscopic photography, primary particles of the sample
were found to be rod-like particles having an average
particle diameter of 30 nm and az~ average particle length
of 200 nm and having an average aspect z~atio of 6.7.
WhEn the resulting sol (M) was transformed into a
coating film, it dried at room temperature within about
10 minutes to afford a film havizzg a film thickness of
18.02.0 ),un and a pencil strength of HB.
Example 7.5
Filtration was carrie3 out in the same manner as
~.n l~xample 14 except that a PA?vt membrane KCP--107.0
(manufactured by Asahx Kasei Corporation) instead of AHP-
1010, whereby a product equal to the sol (A) was obtained.
At this time, clogging with the surfactant was hardly
observed and the filtration. was achieved rapidly. When
the membrane was washed after use, the amount of
permeated water after washing was recovered to a level
which was about the same as that before use.
59
CA 02471714 2004-06-23
Example 16
To the reaction solution obtained in Example 1
was added 17.4 g of 3-(2-
aminoethyl)aminopropyltrimethaxysilane under stirring_
The pH of the mixture was 8_5. then it was stirred at
z5°C for 1 hour, a reaction proceeded and the pH became
8_0, whereby an aggregate was foamed. After the
aggregate was filtered, 20 equivalents of water relative
to the weight of the aggregate was added to disperse it.
The aggrEgate was again filtered and then 26_5 g of 6N
hydrochloric acid was added. Dispersion using an
ultrasonic dispersing machine afforded a product almost
equal to the sol (D) prepared in Example 5.
Example 17
cation exchange resin (Amberlite, IR-120B) and
an anion exchange resin (Amberlite, IR-410) were added to
35000 g of a filtrate (content of Pluronic P123 0.2$b)
obtained in the ultra~iltration step in Example 19, and
the whole was stirred and filtered_ The filtrate was
heated to 60°C and concentrated using MCP-1010 to obtain
8000 g of a 1_2~ by weihgt Pluronic P123 aqueous solution.
At this time, the concentratiot-~ of Pluronic P123 in the
filtrate was 0.01ro. The time required fox the
CA 02471714 2004-06-23
ultrafiltration was 100 minutes. The amount of permeated
water through employed KGP-1010 after washing was
recovered to a le~eZ which was about the same as that
before use. To the concentrate was added 800 g of an
aqueous solution to which 2 g of Pluronic P123 had been
dissolved, and operations the same as in Example 1 were
conducted to obtain a product almost equal to the sol (A)
prepared in Example 1.
example 18
Concentration of the Pluronic was conducted in
the same manner as the concentration step in Example 17
except that a cellulose membrane C030F (manufactured by
Nadia) was used instead of KCP-1010_ The time required
fdr extraction was about 70 minutes. Moreover, the
amount of permeated water after washing was recovered to
a level which was about the same as that before use_
Example 19
When 100 g of the sol (D) obtained in Example 5
was subjected to distillation under reduced pressure, 50
g of a transparent sol (N) of a porous substance having
an Si02 concentration of 14~ by weight was obtained. The
viscosity of the sol was 30 cP_ When the sol (N) was
transformed into a coating film, it dried at room
61
CA 02471714 2004-06-23
temperature within about 40 minutes to afford a film
having a film thickness of 30_0~1.5 ~1m and a pencil
strength of F_
Example 20
Tnto a dispersion of 864 g of a cation-exchange
resin (Amberlite, IR-1208) converted to H+~type beforehand
in 864 g of water was added a solution of 288 g of water
glass No. 3 (Si02 - 29$ by weight, Na20 = 9.5~ by weight)
and 0_228 g of sodium alumznaLe (A12O3 --- 54.9ro by.weight)
diluted with 5?6 g of water. After the mixture was
thoroughly stirred, the catioa:-erchange resin was
filtered off to obtain 1728 g of an active szlica aqueous
solution. The SiOz concentration of the active silica
solution was 5_0~ by weight and the elemental ratio of
Si/A1 was 450.
zn 2296 g of water was dissolved 109 g of
Pluronic P123 manufactured by Asahz ~enka, and 1600 g of
the above actzve silica aqueous solution was added
thereto under stirring at a constant additzon rate in a
water bath at 35°C over a period of 10 minute. The pH of
the mixture was 3.5. At this time, the weight ratio of
water/P123 was 38_5 and the weight ratio of Q123/SiOZ was
1_3. After the mixture was stirred at 35°C for 15 minutes,
it was allowed to stand at 95°C and a reaction was
62
CA 02471714 2004-06-23
effected for 24 hours.
P123 was removed from the solution using an
ultrafiltration apparatus to obtain a sol (Q) of a porous
substance having an Si02 concentration of 7.3b by weight.
The average particle diameter of the sample in the sol
(O) measured by dynamic light scattering method was 195
nm and the converted specific surface area was 14 mz/g.
The sol was dried at 105°C to obtain a porous substance.
The average pore diameter of the sample was 10 nm and the
pare volume was 1.06 ml/g. The nitrogen-absorption
specific surface area by the BET method was 590 mz/g and
the difference from the converted specific surface area
was 576 m2/g_ When observed by an electron microscopic
photography, primaxy particles of the sample were found
to be rod~like particles having an average particle
diameter of 35 nm and an average particle length of 190
nm and having an average aspect ratio of 5_4_
The resulting sol (O) was transformed into a
coating tilm_
example 21
Extraction was Conducted in the same manner as in
Example 14 except that the reaction solution was
maintained at 25°C. The concentration of X123 in the
filtrate was 0.1$.
63
CA 02471714 2004-06-23
Example 22
Extraction of the Pluronic was conducted in the
same manner as Example 1~ except that a polysulfone
membrane SLP-1053 (manufactured by Asahi Kasei
Corporation) was used instead. of AHP-1010. As compared
with AHP-1010, a flux decreased but the extraction was
possible_
Example 23
Extraction of the Pluronic was conducted in the
same manner as Example 14 except that the ultrafiltration
was conducted at pH g.0 without adding NaOH. At the
point that the reaction solution was concentrated to an
Sip2 concentration of 2b, a flow rate decreased but the
extraction was possible.
Example 2~
Concentration o~ the Pluronic was conducted in
the same manner as Example 17 except that the solution
temperature was maintained at 25°C_ The concentration of
Pluronic P123 in 8,000 g of the concentrated solution was
0.30a and the concentration of PZuronic P123 in 27,000 g
of the filtrate was 0.2?~.
64
CA 02471714 2004-06-23
Example 25
Concentration of the Pluronic was conducted in
the same manner as the cpncentxation step in Example 19
except that a polysulfone membrane SLP-1053 was used
instead of KCP-1010. The concentration takes 150 minutes.
The amount of permeated water after washing was 90b of
the amount before use_
Comparative Example 1
A sol (P) having a silica concentration of 7.20
by weight was obtained in the same manner as in Example 1
except that the active silica aqueous solution was added
over an addition period of 3 seconds. When observed by
an electron microscopic photography, primary particles of
the sample were found to be rod,like particles having an
average particle diameter of 30 nm and an average
particle length of 50 nm and having an average aspECt
ratio of 1.7_ The resulting sol (P) was transformed into
a coating film.
CA 02471714 2004-06-23
fable 1
Tnk absorbing Water Light
ro ert resistance resistance
Exam le 1 G B F
Exam le 3 G B G
Exam le 4 G B G
Exam 1e 5 G G F
Exam J.e 6 G F F
Exam le 7 G G F
Exam le 8 G G F
Exam le 9 _ G F
G
Exam 12 10 G G F
Exam le 20 G B F
Comparative ~ B ~ B ~ B
Example 1
Table 2
Sol Viscosity Drying film Pencil
(cF) rate thickness strength
(min
Exam lE A) 360 10 18_Ot2.0 HB
1
Example (J) 350 10 18_O~x_5 H
11
Example (K) 950 120 20_00.5 IiB
12
Example (Z) 10 10 16_01_5 IiB
13
Example (M) 280 40 18_Ot2.0 HB
14
Example (N) 300 40 30_Ot2.0 F
19 ~
~
While the invention has been described in detail.
and with reference to specific examples thereof, it w~.Zl
be apparent to one skilled in the art that various
changes and modifications can be made therein without
departing from the spirit arzd~scope thereof.
The present application is based on Japanese
Patent Application No. 2001-391215 filed on December 25,
CA 02471714 2004-06-23
2001, and the contents are incorporated herein by
reference.
industrial Applicability
Since the porous substance of the invention has
pores and is a fine particulate, an effect of absorption
of substances inside, an effect of protection by
inclusion, and an effect of sustained release are
expected. Furthermore, it is possible to apply it to
fields requiring transparency, smoothness, and the like.
Since the porous substance of the invention has a
large average aspect ratio and packing of the particles
is microscopically loose, a large amount of substances
can be easily held and diffusion is also fast.
By the treatment with a szlane coupling agent at
the production of the porous substance of the invention,
it is possible to produce a sol which is stable even when
zt is acidified ox a cationic substance is added thereto
and which is also durable to long-term storage.
The ink-jet recording medium of the invention has
excellent effects on ink absorbing property and
transparency.
67
